Mechanical atomizing burner



P. L. c. BLANCHARD MECHANICAL ATOMIZING BURNER Jan. 19, 1943.

Filed Feb. 24., 1959 Patented Jan. 19, 1943 MECHANICAL ATOMIZING BURNER Paul Louis Charles Blanchard, Paris, France; vested in the Alien Property Custodian Application February 24, 1939, Serial No. 258,313

In France February 25, 1938 6 Claims.

It is already known in the construction of mechanical atomizing burners, to provide behind the atomizing orifice for the liquid under pressure, an atomizing chamber in which the liquid enters by the periphery and follows a substantially helical path of decreasing pitch up to the atomizing orifice.

Usually, in devices of this type, the diameter of the atomizing chamber gradually decreases up to the central orifice.

The present inventor has found that in devices thus constructed, the speed of the liquid particles projected through the central atomizing orifice is relatively great in the axial longitudinal direction and fairly small in the direction perpendicular to the axis, so that the projection cone is not very open and the flame is shaped like an elongated paint-brush.

In numerous cases, it is important to obtain a better spreading of the atomization in width, so as to produce a much more intimate mixture of the atomized. liquid particles with the air and thereby obtain a wider flame.

The present invention has for its object im provements in mechanical atomization burners, which enable this result to be obtained. Said invention consists in providing the atomizing chamber with a bottom 01 increasing depth from the periphery towards the centre.

The shape, which is theoretically the best in this respect, appears to the inventor to be that of a hyperboloid of revolution having as its axis that of the burner.

The inventor has found, in fact, that under these conditions, for the particles located at the periphery of the fluid stream, the centripetal speed and the axial speed are reduced to a minimum, whereas the tangential speed remains at a maximum. Preferably, the peripheral inlet orifices for the liquid into said atomizing chamber are located as close as possible to the plane of the central atomizing orifice proper.

The invention furthermore comprises a number of features relating to the practical construction of the atomizing chamber thus defined, and which will be described hereinafter with reference to the accompanying drawing.

By way of example, and in order to facilitate I the comprehension of the description, modifications of construction of the burner according to the invention have been shown in axial longitudinal section in Figs. 1 to '7.

Fig. 8 is a cross-sectional view showing the conduits for feeding'fuel to the whirl chamber. In the example shown in Fig. 1, the burner is composed of an outer sleeve I, the front partition of which is provided with a central atomizing hole 2. Behind said atomizing'orifice is provided an atomizing chamber 3 into which the liquid under pressure is supplied through obliquely directed peripheral orifices 4 which are themselves supplied by the pipes 5.

According to the invention, the end B of the atomizing chamber is of increasing depth from the periphery to the centre. In this example. it is shaped like a cone and is formed in a movable part 1 which is movable longitudinally along the axis of the burner and which enables the capacity of the atomizing chamber, and consequently the influence of the conical end on the shape of the atomized sheet, to be varied at will. The extreme front position of said end has been shown in dotted lines in the accompanying drawing.

The liquid which enters through the orifices 4, which are arranged right against the front wall 8 of the atomizing chamber, encounter as they enter the latter a space which widens after the manner of a diffuser, and the liquidstreams follow a path such that the axial speed is extremely low.

In this embodiment, the shape of the bottom of the atomizing chamber has been chosen conical, but it would. appear that the theoretically best shape for keeping the axial speed very low and the centripetal component constant throughout the travel of the liquid in the atomizing chamber, is a surface of revolution, having a hyperbola as its generatrix, the same axis as the burner, and being substantially of the shape shown in Fig. 3. Moreover, any other approaching shapes may be chosen, according to the efiect to be obtained, and sufliciently close to the best theoretical conditions, on the one hand for the spreading eiiect to be obtained, and on the other hand for machining to remain easy to effect.

It has been found by' the inventor that this shape of the bottom of the atomization chamber produces a real suction effect in the axial zone, and owing to this fact it may be advantageous to provide an escape duct for the fluid, starting from the centre of said bottom, as shown in Fig. 2.

A means for adjusting said escape duct, not

shown in the drawing, may be provided for controlling the quantity of liquid which can thus be evacuated.

It is moreover also possible to combine with said bottom escape orifices placed at various points and in particular, as shown in Fig. 3, to

provide simultaneously a central escape conduit 9 and peripheral escape conduits l0.

' These arrangements enable atomization orifices to be formed of relatively large diameter and it has been found that for large discharges the atomization conditions for the liquid located at the centre of the stream are not the same and are more unfavorable than those for the parts of liquid located at the periphery of the stream. Under these conditions, it may be advantageous, as shown in Figs. 4, 5 and 6, to reduce the unfavorable influence of said centre by adding an axial needle ll passing through the centre of the atomizing orifice. According to cases, said needle may be cylindrical, as in Fig. 4, of tapered conical shape, as in Fig. 5, or of flared conical shape, as in Fi 6.

Said needle may either be secured to the bottom I 2 of the atomizing chamber, as shown in Fig. 4, in which case said needle moves with said bottom, or provision may b made for the needle to move relatively to the bottom, as shown in Figs. 5 and 6, thereby enabling the position of the needle to be adjusted independently.

It is also possible, as shown in Fig. 6, to combine the addition of said needle with an escape duct 13 which surrounds same and performs the same function as the ducts 9 of Figs. 2 and 3. It should moreover be noted that it would also be possible to improve the emciency of known burners, which do not comprise an atomizing end that complies with the above definition, by adding said central needle.

Finally, the liquid supply orifices 4 should be placed as close as possible to the plane which is perpendicular to the axis of the burner and in which is located the atomizing orifice 2. However, it is possible to add to said orifices 4, secondary supply orifices such as I! (Fig. 7) which are distributed depthwise and are successively uncovered by the variations of position of the movable end 1, so as to enable the discharge to be varied. The suction effect towards the rear, which is due to the shape of the end I, prevents the distance between the orifices I4 and the atomizing orifice 2 from producing an unfavorable effect.

I claim:

1. A mechanical atomizing liquid fuel burner comprising a whirl chamber having a front wall plane and perpendicular to the longitudinal axis of said chamber, a side wall symmetrical about the longitudinal axis and a rear wall in which the points thereof furthest from said front wall are located nearest the longitudinal axis of said chamber, said rear wall forming a surface of revolution symmetrical about said axis, openings in said side wall to direct fuel into said chamber substantially tangentially to said side wall, the

axes of said openings being located in a plane perpendicular to the longitudinal axis of said chamber and also being tangent to said front wall and a short atomizing nozzle opening extending through said front wall between said chamber and the combustion space and emerging from said whirl chamber substantially perpendicular to the front wall thereof and coaxially of said whirl chamber.

2. A fuel burner as set forth in claim 1 in which said rear wall of said chamber is movable and means are provided for adjusting the position of said rear wall.

3. A burner as set forth in claim 1 in which said rear wall of said whirl chamber has a conical form.

4. A burner as set forth in claim 1 in which said rear wall of said whirl chamber has the form of a hyperbola of revolution.

5. A burner as set forth in claim 1 in which said rear wall of said whirl chamber is provided with an escape port in order to evacuate excess fuel.

6. A burner as set forth in claim 1 in which said rear wall of said whirl chamber is provided with an escape port in order to evacuate excess fuel located adjacent the periphery of said chamber.

PAUL LOUIS CHARLES BLANCHARD. 

